I'm going to try to poke holes in your system. I'm not doing this because I'm a meany head. This is meant to be constructive criticism.
If you want fairly deadly combat, you can use Stress as HP. Your track starts out at 5, increasing as normal. If someone hits you with an attack for 3 stress, you lose three boxes. It tends to bring the Consequences a little more quickly.
Letting stress stick around might be a bad idea. It makes it really difficult to have multiple conflicts in one session. If you run it close to the way the books work, you'll never have a day of down time, so you'll never recover from stress. Taking Consequences should be enough to model the way Harry tends to end up.
I'm a fan of using a small set of systems and avoiding building sub-systems. Much of what follows represents that tendency.
I'm also not sure why you're putting so much system band width toward armour. You can easily model armour with Aspects and Stunts. This lets you use the same Stunts to model creatures that are supernaturally tough. You could, for example, have a stunt that reduced incoming physical stress by 1 points, but it has a flaw. "Needs to be wearing armour," is a pretty good flaw. You could then use the same Stunt to represent something that's supernaturally resilient except against fire. Doing this also mitigates any need to spend valuable skill points on a skill to use it; that's a really narrow skill.
Requiring a Stunt to have protection offers you the chance to avoid people getting mechanical benefits for free, if that's something you're worried about.
You can model the disadvantages of armour with a proper Aspect. "Uses a full suit of metal armour," works. Compels have him unable to go certain places, having difficulty being stealthy, etc. Invocations let him defend himself or add to unarmed rolls to smash someone with his big gauntlets.
I'm not certain of the need for a Concentration skill. Almost every instance I can think of in the books where someone needed to concentrate, I'd model it as a skill roll.
What skill are you using for magic?
Finally, I suggest using what some of us have been calling generic Stunts. A purchase of a Stunt might allow you to:
* Add +1 to a given skill roll under a set of circumstances. For example, using Science for medical purposes.
* Add +2 to a given skill roll under a narrower set of circumstances. Using Science to treat a poison victim.
* Use one skill in the place of another under a set of circumstances. Using Magic in the place of Guns if you have a focus, in which case you can blast something with fire, wind, or force.
* Have a gadget.
* Have a minion. Build using the generic minion rules.
You could probably have some that generically increase or decrease stress, the defensive one having some hole as above. Adding a single Consequence also makes sense; you might allow this to add a higher level of Consequence if it has a defensive hole.